Postby Cary Bailey » July 6th, 2017, 2:00 pm
Stuart, 3W are slightly ambitious in their rpm info. On the basis that you have your cooling of the motor sorted and the general normal things needed to run this engine then there are several things to note, fuel/oil ratio, type of oil you are using plus the ignition module.
3W say use 50 or even 80:1 fuel oil ratio, I always use around 50:1. 50:1 and lower can actually reduce the rpm in 2 factors, too much oil around the needle bearings can actually make them "slide" as opposed to roll. This causes excessive heat and the engine rpm drops due to this even though you have increased the oil thinking the engine will benefit from this and the cooling property of the oil. This causes the heat, the heat then richens up the fuel setting and the rpm drops off!
I use a good quality 2 stroke oil such as Bel-Ray, Redline, Castrol. Using the cheaper oils can cause problems and higher levels of carbon deposits.
3W ignition unit, here I have a problem in that I have 2 3W 55i's that I could never get them to perform at higher rpm's. I was only getting as you are around the 5700-6000 rpm on a 22x10 Menz or Falcon prop. I changed the 3W ignition unit to the Rcxel unit and immediately got an additional 1000-1300 rpm!
Just some pointers that you probably know but that is my experience with them.
Cary